(1.) Field of the Invention
The present invention relates to a temperature-compensating voltage generator circuit used in an electric device whose temperature characteristics can be controlled by a control voltage. The temperature-compensating voltage generator circuit according to the present invention is preferably used, for example, in an oscillation frequency stabilizing circuit of a high-stability feedback type dielectric oscillator used in the microwave frequency band.
(2.) Description of the Prior Art
The oscillation frequency of a feedback type of dielectric oscillator used in the microwave frequency band varies depending on the gate bias voltage as well as on the ambient temperature. Therefore, it is possible to compensate the temperature characteristic of the oscillation frequency by controlling the gate bias voltage. If the temperature characteristic is compensated by controlling the gate bias voltage, it is usually compensated by, at first, measuring the temperature characteristic of an electric circuit in which the temperature characteristic is to be compensated and then by selecting and adjusting a control voltage generating circuit in accordance with the temperature characteristic.
The above-mentioned method involves practically no problems when it is used for electric circuits having a constant-slope temperature characteristic because it is not necessary to adjust the compensating circuit for individual electric circuits. However, when the above-mentioned method is used for electric circuits each having a different temperature characteristic or a temperature characteristic not having a constant slope, the process of selecting and adjusting the above-mentioned control voltage generator becomes very complicated.
In order to solve the above-mentioned problem, in U.S. Pat. No. 4,352,053, which is assigned to the assignee of the present invention, a temperature-compensating voltage generator circuit wherein the control voltage at any temperature can be adjusted without exerting a great influence on the control voltage adjusted at other temperatures. However, in this temperature-compensating voltage generator circuit, it is impossible to adjust the control voltage at any temperature without exerting any influence on the control voltage at other temperatures.